Quaternary ammonium fuel additives

ABSTRACT

The present disclosure provides fuel additives including a quaternary ammonium salt formed by reacting an alkyl carboxylate with a compound formed from a hydrocarbyl substituted acylating agent reacted with a select amine. Also provided herein are fuel compositions including the novel fuel additives and methods of combusting a fuel including the fuel additives herein. The unique quaternary ammonium salts herein are advantageous because they can be made through a simple alkylation process and provide improved detergency at low treat rates by making available a relatively less sterically hindered quaternary nitrogen for detergency activity in the fuel.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/009,403 filed Jun. 15, 2018, which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

This disclosure is directed to fuel additive compositions that includehydrocarbyl soluble quaternary ammonium salts and to methods for usingthe salts in a fuel composition as fuel detergents.

BACKGROUND

Fuel compositions for vehicles are continually being improved to enhancevarious properties of the fuels in order to accommodate their use innewer, more advanced engines. Often, improvements in fuel compositionscenter around improved fuel additives and other components used in thefuel. For example, friction modifiers may be added to fuel to reducefriction and wear in the fuel delivery systems of an engine. Otheradditives may be included to reduce the corrosion potential of the fuelor to improve the conductivity properties. Still other additives may beblended with the fuel to improve fuel economy. Engine and fuel deliverysystem deposits represent another concern with modern combustionengines, and therefore other fuel additives often include variousdeposit control additives to control and/or mitigate engine depositproblems. Thus, fuel compositions typically include a complex mixture ofadditives.

However, there remain challenges when attempting to balance such acomplex assortment of additives. For example, some of the conventionalfuel additives may be beneficial for one characteristic, but at the sametime be detrimental to another characteristic of the fuel. Other fueladditives often require an unreasonably high treat rate to achieve theirdesired effect, which tends to place undesirable limits on the availableamounts of other additives in the fuel composition.

Quaternary ammonium compounds, such as alkoxylated salts, have recentlybeen developed as detergents for fuels. The quaternary ammoniumcompounds, in some instances, are obtained from an acylating agentreacted with a polyamine, which is then alkylated or quaternized by aquaternizing agent. While providing improved detergency compared toprior detergents, these quaternary ammonium compounds and their methodsof alkylation, however, still have several shortcomings. For example, insome instances, ethylene oxides and propylene oxides are used to makesuch detergents. Such oxides, however, are often undesired due to theirhandling difficulties. Quaternary ammonium compounds may also be formedthrough alkylation using dialkyl carbonates. However, the carbonateanion may be susceptible to precipitation and drop out of certain typesof fuels or fuel additive packages. Other quaternary ammonium saltsrequire halogenated carboxylic acids as quaternary agents. These saltsmay include residual halogens that may be less preferred in someapplications. In yet other instances, removing undesirable ashgenerating components from the quaternizing manufacturing process iscomplicated.

While offering an improvement in detergency, prior quaternary ammoniumcompounds still have limitations in that relatively higher treat ratesmay be required to achieve adequate detergency effect in someapplications. Often the pendant quaternary nitrogen in the quaternaryammonium salt is a derived from a diamine, such as dimethylaminopropylamine, a common tertiary diamine obtained from the Michaelreaction between dimethylamine and acrylonitrile through a subsequenthydrogenation. This diamine is a commonly available and convenient amineto form a quaternary ammonium salt. However, when using such tertiaryamine source in a quaternizing reaction, it is often hindered in itsavailability for alkylation and/or activity as a detergent. As a result,quaternary ammonium salts obtained from such tertiary amines may not besufficiently effective for improving injector performance at relativelylow treat rates.

SUMMARY

In one aspect, a fuel additive is provided that includes a quaternaryammonium salt formed by the reaction of an alkyl carboxylate with anamide or imide compound obtained by reacting a hydrocarbyl substitutedacylating agent and an amine, wherein the amine has the structure ofFormula I

Wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, —C(O)NR′; R₁ and R₂ are independently alkyl groupscontaining 1 to 8 carbon atoms; and R′ is independently a hydrogen or agroup selected from C₁₋₆ aliphatic, phenyl, or alkylphenyl.

The fuel additive of the preceding paragraph may be combined with one ormore optional features either individually or in any combinationthereof. These optional features include: wherein the alkyl carboxylateis alkyl oxalate, alkyl salicylate, or a combination thereof; and/orwherein the alkyl group in the alkyl carboxylate is C₁ to C₆ alkyl;and/or wherein A is —(CH₂)_(r)—[X—(CH₂)_(r′)]_(p)— with each of r, r′,and p independently being 1, 2, 3, or 4 and X being oxygen or NR″ withR″ being hydrogen or a hydrocarbyl group; and/or wherein X is oxygen;and/or wherein the amine is selected from3-(2-(dimethylamino)ethoxy)propylamine, N,N-dimethyl dipropylenetriamine, and mixtures thereof; and/or wherein the hydrocarbylsubstitued acylating agent is selected from a hydrocarbyl substituteddicarboxylic acid or anhydride derivative thereof, a fatty acid, ormixtures thereof; and/or wherein the hydrocarbyl substituent has anumber average molecular weight of about 200 to about 2500 as measuredby GPC using polystyrene as a calibration reference.

In another aspect, the present disclosure provides a fuel compositioncomprising a major amount of a fuel and a minor amount of, in oneaspect, a quaternary ammonium salt formed by the reaction of an alkylcarboxylate with an amide or imide compound obtained by reacting ahydrocarbyl substituted acylating agent and an amine of Formula I above.In another aspect, the fuel composition includes the formed quaternaryammonium salt of the structure of Formula II

Wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, or —C(O)NR′; R₁, R₂, and R₃ are independently alkylgroups containing 1 to 8 carbon atoms; and R′ is independently ahydrogen or a group selected from C₁₋₆ aliphatic, phenyl, oralkylphenyl; and R₄ and R₅ are independently a hydrogen, an acyl group,or a hydrocarbyl substituted acyl group, wherein if one of R₄ or R₅ ishydrogen, then the other of R₄ and R₅ is the acyl group or thehydrocarbyl substituted acyl group, and if both R₄ and R₅ includecarbonyl moieties, then one of R₄ and R₅ includes the acyl group and theother of R₄ and R₅ includes the hydrocarbyl substitued acyl group, andR₄ and R₅ together with the N atom to which they are attached, combineto form a ring moiety; and M⁻ is a carboxylate.

The fuel additive of the preceding paragraph may be combined with one ormore optional features either individually or in any combinationthereof. These optional features include: wherein the fuel compositionincludes about 1 to about 100 ppm of the quaternary ammonium salt;and/or wherein the carboxylate is oxalate, salicylate, or combinationsthereof; and/or wherein A is —(CH₂)_(r)—[X—(CH₂)_(r′)]_(p)— with each ofr, r′, and p independently being 1, 2, 3, or 4 and X being oxygen or NR″with R″ being hydrogen or a hydrocarbyl group; and/or wherein X isoxygen; and/or wherein A includes a moiety derived from3-(2-(dimethylamino)ethoxy) propylamine,N,N-dimethyldipropylenetriamine, or mixtures thereof; and/or wherein R₄and R₅, together with the nitrogen atom to which they are attached,combine to form a hydrocarbyl substituted succinimide; and/or whereinthe hydrocarbyl substituent has a number average molecular weight ofabout 200 to about 2500 as measured by GPC using polystyrene as acalibration reference; and/or wherein the hydrocarbyl substituent of R₄or R₅ has a number average molecular weight of about 200 to about 2500as measured by GPC using polystyrene as a calibration reference.

In yet a further aspect, the present disclosure provides a method ofoperating a fuel injected engine to provide improved engine performance,such as but not limited to, reducing injector deposits in an internalcombustion engine or fuel system for an internal combustion engine,cleaning-up fouled injectors, or un-sticking injectors. The methodsherein include combusting in the engine a fuel composition including amajor amount of fuel and about 1 to about 100 ppm of a quaternaryammonium salt formed by the reaction of an alkyl carboxylate with anamide or imide compound obtained by reacting a hydrocarbyl substitutedacylating agent and an amine, wherein the amine has the structure

Wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, or —C(O)NR′; R₁ and R₂ are independently alkyl groupscontaining 1 to 8 carbon atoms; and R′ is independently a hydrogen or agroup selected from C₁₋₆ aliphatic, phenyl, or alkylphenyl. The presentdisclosure also provides for the use of the above described quaternaryammonium salt for providing improved engine performance, such as but notlimited to, reducing injector deposits in an internal combustion engineor fuel system for an internal combustion engine, cleaning-up fouledinjectors, or un-sticking injectors.

The methods or use described in the preceding paragraph may be combinedwith one or more optional features either individually or in anycombination thereof. These optional features include: wherein theimproved engine performance is an average flow loss of about 45 percentor less when measured according to a CEC F-23-01 (XUD-9) test; and/orwherein the formed quaternary ammonium salt has the structure

Wherein A includes 2 to 6 carbon units with one carbon unit thereofindependently replaced with —O— or —NH—; and/or wherein R₁, R₂, and R₃are independently alkyl groups containing 1 to 8 carbon atoms; and/orwherein R₄ and R₅ are independently a hydrogen, an acyl group, or ahydrocarbyl substituted acyl group; and/or wherein if one of R₄ or R₅ ishydrogen, then the other of R₄ and R₅ is the acyl group or thehydrocarbyl substituted acyl group, and if both R₄ and R₅ includecarbonyl moieties, then one of R₄ and R₅ includes the acyl group and theother of R₄ and R₅ includes the hydrocarbyl substitued acyl group, andR₄ and R₅ together with the N atom to which they are attached, combineto form a ring moiety; and/or wherein M⁻ is a carboxylate; and/orwherein the carboxylate is oxalate, salicylate, or combinations thereof;and/or wherein the hydrocarbyl substituent has a number averagemolecular weight of about 200 to about 2500 as measured by GPC usingpolystyrene as a calibration reference; and/or wherein A is—(CH₂)_(r)—[X—(CH₂)_(r′)]_(p)— with each of r, r′, and p independentlybeing 1, 2, 3, or 4 and X being oxygen or NR″ with R″ being hydrogen ora hydrocarbyl group; and/or wherein X is oxygen.

DETAILED DESCRIPTION

The present disclosure provides fuel additives including a quaternaryammonium salt formed by reacting an alkyl carboxylate with an amide orimide compound formed by reacting a hydrocarbyl substituted acylatingagent with a select amine. Also provided herein are fuel compositionsincluding the novel fuel additives and methods of combusting a fuelincluding the fuel additives herein. The unique quaternary ammoniumsalts herein are beneficial because they can be made through a simplealkylation process and provide improved detergency at low treat rates bymaking available a relatively less sterically hindered quaternarynitrogen for detergent activity in the fuel.

In one aspect of this disclosure, an exemplary fuel additive including aquaternary ammonium salt may be formed through a reaction between analkyl carboxylate and an amide or imide compound obtained by reacting ahydrocarbyl substituted acylating agent and an amine. In one approach ofthis aspect, the amine has the structure of Formula I

Wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, and —C(O)NR′. R₁ and R₂ are independently alkyl groupscontaining 1 to 8 carbon atoms, and R′ is independently a hydrogen or agroup selected from C₁₋₆ aliphatic, phenyl, or alkylphenyl. In anotherapproach of this aspect, the formed quaternary ammonium salt may be thatof Formula II discussed below.

In another aspect of this disclosure, a fuel composition is providedincluding a major amount of a fuel and a minor amount of a quaternaryammonium salt formed by the reaction of an alkyl carboxylate with anamide or imide compound obtained by reacting a hydrocarbyl substitutedacylating agent and an amine, which may be the amine of Formula I above.In one approach of this aspect, the formed quaternary ammonium salt hasthe structure of Formula II

Wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, and —C(O)NR′. R₁, R₂, and R₃ are independently alkylgroups containing 1 to 8 carbon atoms; and R′ is independently ahydrogen or a group selected from C₁₋₆ aliphatic, phenyl, oralkylphenyl. R₄ and R₅ are independently a hydrogen, an acyl group, or ahydrocarbyl substituted acyl group. If one of R₄ or R₅ is hydrogen, thenthe other of R₄ and R₅ is the acyl group or the hydrocarbyl substitutedacyl group. If both R₄ and R₅ include carbonyl moieties, then one of R₄and R₅ includes the acyl group and the other of R₄ and R₅ includes thehydrocarbyl substitued acyl group, and R₄ and R₅ together with the Natom to which they are attached, combine to form a ring moiety. In otherapproaches, R₄ and R₅ together with the N atom to which they areattached, combine to form a hydrocarbyl substituted succinimide. M⁻ is acarboxylate.

In yet another aspect of this disclosure, a method of operating a fuelinjected engine to provide improved engine performance is described. Themethod includes combusting in the engine a fuel composition including amajor amount of fuel and about 1 to about 100 ppm of a quaternaryammonium salt formed by the reaction of an alkyl carboxylate with anamide or imide compound obtained by reacting a hydrocarbyl substitutedacylating agent and an amine, wherein the amine has the structure ofFormula I or the resulting quaternary ammonium salt has the structure ofFormula II. In yet further aspects, a use of the quaternary ammoniumsalts as described in the previous paragraphs is provided to provideimproved engine performance such as a reduced average flow loss of about45% or less as evaluated by XUD-9, a power recovery of about 65 percentor greater as measured by a CEC F-98-08 test modified to evaluate theability of an additive to restore power lost due to deposit formation,and/or removal of carboxylate deposits and unsticking injectors on acold start.

As used herein, the term “hydrocarbyl group” or “hydrocarbyl” is used inits ordinary sense, which is well-known to those skilled in the art.Specifically, it refers to a group having a carbon atom directlyattached to the remainder of a molecule and having a predominantlyhydrocarbon character. Examples of hydrocarbyl groups include: (1)hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl),alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-,aliphatic-, and alicyclic-substituted aromatic substituents, as well ascyclic substituents wherein the ring is completed through anotherportion of the molecule (e.g., two substituents together form analicyclic radical); (2) substituted hydrocarbon substituents, that is,substituents containing non-hydrocarbon groups which, in the context ofthe description herein, do not alter the predominantly hydrocarbonsubstituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy,mercapto, alkylmercapto, nitro, nitroso, amino, alkylamino, andsulfoxy); (3) hetero-substituents, that is, substituents which, whilehaving a predominantly hydrocarbon character, in the context of thisdescription, contain other than carbon in a ring or chain otherwisecomposed of carbon atoms. Hetero-atoms include sulfur, oxygen, nitrogen,and encompass substituents such as pyridyl, furyl, thienyl, andimidazolyl. In general, no more than two, or as a further example, nomore than one, non-hydrocarbon substituent will be present for every tencarbon atoms in the hydrocarbyl group; in some embodiments, there willbe no non-hydrocarbon substituent in the hydrocarbyl group.

As used herein, the term “major amount” is understood to mean an amountgreater than or equal to 50 wt. %, for example from about 80 to about 98wt. % relative to the total weight of the composition. Moreover, as usedherein, the term “minor amount” is understood to mean an amount lessthan 50 wt. % relative to the total weight of the composition.

Amine Compound

In one embodiment, the fuel additives herein are obtained from a selectamine having the structure of Formula I

Wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, and —C(O)NR′. R₁ and R₂ are independently alkyl groupscontaining 1 to 8 carbon atoms, and R′ is independently a hydrogen or agroup selected from C₁₋₆ aliphatic, phenyl, or alkylphenyl. In oneapproach, the select amines of Formula 1 are at least diamines ortriamines having a terminal primary amino group on one end for reactionwith the hydrocarbyl substituted acylating agent and a terminal tertiaryamine on the other end for reaction with the quaternizing agent. Inother approaches, A includes 2 to 6 carbon units with one carbon unitthereof replaced with a —O— or a —NH— group. Suitable exemplary tertiaryamine for forming the fuel additives herein may be selected from3-(2-(dimethylamino)ethoxy)propylamine, N,N-dimethyl dipropylenetriamine, and mixtures thereof. In other embodiments or approaches, Ahas the structure —(CH₂)_(r)—[X—(CH₂)_(r′)]_(p)— with each of r, r′, andp independently being an integer 1, 2, 3, or 4 and X being either oxygenor NR″ with R″ being hydrogen or a hydrocarbyl group. In otherembodiments, X is oxygen. In yet other embodiments, X is —NH—.

The hydrocarbyl linker A preferably has 1 to 4 carbon units replacedwith the bivalent moiety described above, which is preferably a —O— or a—NH— group. In other approaches, 1 to 2 carbon units of the hydrocarbyllinker A and, in yet further approaches, 1 carbon unit of thehydrocarbyl linker A is replaced with the bivalent moiety describedherein. As appreciated, the remainder of the hydrocarbyl linker A ispreferably a carbon atom(s). The number of carbon atoms on either sideof the replaced bivalent moiety need not be equal meaning thehydrocarbyl chain between the terminal primary amino group and theterminal tertiary amino group need not be symmetrical relative to thereplaced bivalent moiety.

Hydrocarbyl Substituted Acylating Agent

Any of the foregoing described tertiary amines may be reacted with ahydrocarbyl substituted acylating agent that may be selected from ahydrocarbyl substituted mono- di- or polycarboxylic acid or a reactiveequivalent thereof to form an amide or imide compound. A particularlysuitable acylating agent is a hydrocarbyl substituted succinic acid,ester, anhydride, mono-acid/mono-ester, or diacid. In some approaches,the hydrocarbyl substituted acylating agent is a hydrocarbyl substituteddicarboxylic acid or anhydride derivative thereof, a fatty acid, ormixtures thereof.

In other approaches, the hydrocarbyl substituted acylating agent may becarboxylic acid or anhydride reactant. In one approach, the hydrocarbylsubstituted acylating agent may be selected from stearic acid, oleicacid, linoleic acid, linolenic acid, palmitic acid, palmitoleic acid,lauric acid, myristic acid, myristoleic acid, capric acid, caprylicacid, arachidic acid, behenic acid, erucic acid, anhydride derivativesthereof, or a combination thereof.

In one approach, the hydrocarbyl substituted acylating agent is ahydrocarbyl substituted dicarboxylic anhydride of Formula Iii

wherein R₆ is a hydrocarbyl or alkenyl group. In some aspects, R₆ is ahydrocarbyl group having a number average molecular weight from about200 to about 2500 For example, the number average molecular weight of R₆may range from about 600 to about 1300, as measured by GPC usingpolystyrene as a calibration reference. A particularly useful R₆ has anumber average molecular weight of about 1000 Daltons and comprisespolyisobutylene.

The number average molecular weight (Mn) for any embodiment herein maybe determined with a gel permeation chromatography (GPC) instrumentobtained from Waters or the like instrument and the data was processedwith Waters Empower Software or the like software. The GPC instrumentmay be equipped with a Waters Separations Module and Waters RefractiveIndex detector (or the like optional equipment). The GPC operatingconditions may include a guard column, 4 Agilent PLgel columns (lengthof 300×7.5 mm; particle size of 5μ, and pore size ranging from 100-10000Å) with the column temperature at about 40° C. Unstabilized HPLC gradetetrahydrofuran (THF) may be used as solvent, at a flow rate of 1.0mL/min. The GPC instrument may be calibrated with commercially availablepolystyrene (PS) standards having a narrow molecular weight distributionranging from 500-380,000 g/mol. The calibration curve can beextrapolated for samples having a mass less than 500 g/mol. Samples andPS standards can be in dissolved in THF and prepared at concentration of0.1-0.5 wt. % and used without filtration. GPC measurements are alsodescribed in U.S. Pat. No. 5,266,223, which is incorporated herein byreference. The GPC method additionally provides molecular weightdistribution information; see, for example, W. W. Yau, J. J. Kirklandand D. D. Bly, “Modern Size Exclusion Liquid Chromatography”, John Wileyand Sons, New York, 1979, also incorporated herein by reference.

In some approaches, the R₆ hydrocarbyl moiety may comprise one or morepolymer units chosen from linear or branched alkenyl units. In someaspects, the alkenyl units may have from about 2 to about 10 carbonatoms. For example, the polyalkenyl radical may comprise one or morelinear or branched polymer units formed from ethylene radicals,propylene radicals, butylene radicals, pentene radicals, hexeneradicals, octene radicals and decene radicals. In some aspects, the R₆polyalkenyl radical may be in the form of, for example, a homopolymer,copolymer or terpolymer. In other aspects, the polyalkenyl radical ispolyisobutylene. For example, the polyalkenyl radical may be ahomopolymer of polyisobutylene comprising from about 5 to about 60isobutylene groups, such as from about 15 to about 30 isobutylenegroups. The polyalkenyl compounds used to form the R₆ polyalkenylradicals may be formed by any suitable methods, such as by conventionalcatalytic oligomerization of alkenes.

In some aspects, high reactivity polyisobutylenes having relatively highproportions of polymer molecules with a terminal vinylidene group may beused to form the R₆ group. In one example, at least about 60%, such asabout 70% to about 90%, of the polyisobutenes comprise terminal olefinicdouble bonds. In some aspects, approximately one mole of maleicanhydride may be reacted per mole of polyalkylene, such that theresulting polyalkenyl succinic anhydride has about 0.8 to about 1.5succinic anhydride group per polyalkylene substituent. In other aspects,the molar ratio of succinic anhydride groups to polyalkylene groups mayrange from about 0.5 to about 3.5, such as from about 1 to about 1.3.

Quaternizing Agent

A suitable alkylating or quaternizing agent is a hydrocarbyl-substitutedcarboxylate, such as an alkyl carboxylate. In some approaches orembodiments, the quaternizing agent is an alkyl carboxylate selectedform alkyl oxalate, alkyl salicylate, and combinations thereof. In otherapproaches or embodiments, the alkyl group of the alkyl carboxylateincludes 1 to 6 carbon atoms, and is preferably methyl groups.

For alkylation with an alkyl carboxylate, it may be desirable in someapproaches that the corresponding acid of the carboxylate have a pKa ofless than 4.2. For example, the corresponding acid of the carboxylatemay have a pKa of less than 3.8, such as less than 3.5, with a pKa ofless than 3.1 being particularly desirable. Examples of suitablecarboxylates may include, but not limited to, maleate, citrate,fumarate, phthalate, 1,2,4-benzenetricarboxylate,1,2,4,5-benzenetetracarboxylate, nitrobenzoate, nicotinate, oxalate,aminoacetate, and salicylate. As noted above, preferred carboxylatesinclude oxalate, salicylate, and combinations thereof.

Quaternary Ammonium Salt

In other approaches or embodiments, the quaternary ammonium salt formedby the reaction of an alkyl carboxylate with an amide or imide compoundobtained by reacting a hydrocarbyl substitued acylating agent and anamine of Formula 1 results in a quaternary ammonium salt having thestructure of Formula IV

Wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, or —C(O)NR′. R₁, R₂, and R₃ are independently alkylgroups containing 1 to 8 carbon atoms; and R′ is independently ahydrogen or a group selected from C₁₋₆ aliphatic, phenyl, oralkylphenyl. R₄ and R₅ are independently a hydrogen, an acyl group(RC(O)—), or a hydrocarbyl substituted acyl group (the hydrocarbylsubstituted acyl group may be derived from a dicarboxylic acid as shownin the exemplary formulas below). In some approaches or embodiments, ifone of R₄ or R₅ is hydrogen, then the other of R₄ and R₅ is the acylgroup or the hydrocarbyl substituted acyl group. In other approaches orembodiments, if both R₄ and R₅ include carbonyl moieties, then one of R₄and R₅ includes the acyl group and the other of R₄ and R₅ includes thehydrocarbyl substitued acyl group, and R₄ and R₅ together with the Natom to which they are attached, combine to form a ring moiety. Thehydrocarbyl substituted acyl group may include a terminal carboxylgroup. M⁻ is a carboxylate, such as oxalate, salicylate, or combinationsthereof.

Suitable examples of the resulting quaternary ammonium salt from theabove described reactions include, but are not limited to compounds ofthe following exemplary structures:

Wherein A, R₁, R₂, R₃, R₆, and M are as described above. R₇ is a C1 toC30 hydrocarbyl group, and R₈ is a C1 to C10 hydrocarbyl linker. Due tothe length of the hydrocarbyl chain A and the presence of the replacingbivalent moiety therein as discussed above, it is believed thequaternary ammonium salts as described herein include a relativelysterically available quaternary nitrogen that is more available fordetergent activity than prior quaternary ammonium compounds.

When formulating the fuel compositions of this application, the abovedescribed additives (reaction products and/or resultant additives asdescribed above) may be employed in amounts sufficient to reduce orinhibit deposit formation in a fuel system, a combustion chamber of anengine and/or crankcase, and/or within fuel injectors. In some aspects,the fuels may contain minor amounts of the above described reactionproduct or resulting salt thereof that controls or reduces the formationof engine deposits, for example injector deposits in engines. Forexample, any embodiments of the fuels of this disclosure may contain, onan active ingredient basis, an amount of the quaternary ammonium salt(or reaction product as described herein) in the range of about 1 ppm toabout 100 ppm, in other approaches, about 5 ppm to about 50 ppm, in yetfurther approaches about 10 ppm to about 25 ppm of the quaternaryammonium salt. It will also be appreciated that any endpoint between theabove described ranges are also suitable range amounts as needed for aparticular application. The active ingredient basis excludes the weightof (i) unreacted components associated with and remaining in the productas produced and used, and (ii) solvent(s), if any, used in themanufacture of the product either during or after its formation.

Other Additives

One or more optional compounds may be present in the fuel compositionsof the disclosed embodiments. For example, the fuels may containconventional quantities of cetane improvers, octane improvers, corrosioninhibitors, cold flow improvers (CFPP additive), pour point depressants,solvents, demulsifiers, lubricity additives, friction modifiers, aminestabilizers, combustion improvers, detergents, dispersants,antioxidants, heat stabilizers, conductivity improvers, metaldeactivators, marker dyes, organic nitrate ignition accelerators,cyclomatic manganese tricarbonyl compounds, carrier fluids, and thelike. In some aspects, the compositions described herein may containabout 10 weight percent or less, or in other aspects, about 5 weightpercent or less, based on the total weight of the additive concentrate,of one or more of the above additives. Similarly, the fuels may containsuitable amounts of conventional fuel blending components such asmethanol, ethanol, dialkyl ethers, 2-ethylhexanol, and the like.

In some aspects of the disclosed embodiments, organic nitrate ignitionaccelerators that include aliphatic or cycloaliphatic nitrates in whichthe aliphatic or cycloaliphatic group is saturated, and that contain upto about 12 carbons may be used. Examples of organic nitrate ignitionaccelerators that may be used are methyl nitrate, ethyl nitrate, propylnitrate, isopropyl nitrate, allyl nitrate, butyl nitrate, isobutylnitrate, sec-butyl nitrate, tort-butyl nitrate, amyl nitrate, isoamylnitrate; 2-amyl nitrate, 3-amyl nitrate, hexyl nitrate, heptyl nitrate,2-heptyl nitrate, octyl nitrate, isooctyl nitrate, 2-ethylhexyl nitrate,nonyl nitrate, decyl nitrate, undecyl nitrate, dodecyl nitrate,cyclopentyl, nitrate, cyclohexyl nitrate, methylcyclohexyl nitrate,cyclododecyl nitrate, 2-ethoxyethyl nitrate, 2-(2-ethoxyethoxy)ethylnitrate, tetrahydrofuranyl nitrate, and the like. Mixtures of suchmaterials may also be used.

Examples of suitable optional metal deactivators useful in thecompositions of the present application are disclosed in U.S. Pat. No.4,482,357, the disclosure of which is herein incorporated by referencein its entirety. Such metal deactivators include, for example,salicylidene-o-aminophenol, disalicylidene ethylenediamine,disalicylidene propylenediamine, andN,N′-disalicylidene-1,2-diaminopropane.

Suitable optional cyclomatic manganese tricarbonyl compounds which maybe employed in the compositions of the present application include, forexample, cyclopentadienyl manganese tricarbonyl, methylcyclopentadienylmanganese tricarbonyl, indenyl manganese tricarbonyl, andethylcyclopentadienyl manganese tricarbonyl. Yet other examples ofsuitable cyclomatic manganese tricarbonyl compounds are disclosed inU.S. Pat. Nos. 5,575,823 and 3,015,668 both of which disclosures areherein incorporated by reference in their entirety.

Other commercially available detergents may be used in combination withthe reaction products described herein. Such detergents include but arenot limited to succinimides, Mannich base detergents, quaternaryammonium detergents, bis-aminotriazole detergents as generally describedin U.S. patent application Ser. No. 13/450,638, and a reaction productof a hydrocarbyl substituted dicarboxylic acid, or anhydride and anaminoguanidine, wherein the reaction product has less than oneequivalent of amino triazole group per molecule as generally describedin U.S. patent application Ser. Nos. 13/240,233 and 13/454,697.

The additives of the present application, including the quaternaryammonium salts described above, and optional additives used informulating the fuels of this invention may be blended into the basefuel individually or in various sub-combinations. In some embodiments,the additive components of the present application may be blended intothe fuel concurrently using an additive concentrate, as this takesadvantage of the mutual compatibility and convenience afforded by thecombination of ingredients when in the form of an additive concentrate.Also, use of a concentrate may reduce blending time and lessen thepossibility of blending errors.

Fuels

The fuels of the present application may be applicable to the operationof diesel, jet, or gasoline engines. In one approach, the quaternaryammonium salts herein are well suited for diesel or gasoline as shown inthe Examples. In one embodiment, the fuel is diesel fuel. In anotherembodiment, the fuel is gasoline. In yet another embodiment, the fuel isa jet fuel. The fuels may include any and all middle distillate fuels,diesel fuels, biorenewable fuels, biodiesel fuel, fatty acid alkylester, gas-to-liquid (GTL) fuels, gasoline, jet fuel, alcohols, ethers,kerosene, low sulfur fuels, synthetic fuels, such as Fischer-Tropschfuels, liquid petroleum gas, bunker oils, coal to liquid (CTL) fuels,biomass to liquid (BTL) fuels, high asphaltene fuels, fuels derived fromcoal (natural, cleaned, and petcoke), genetically engineered biofuelsand crops and extracts therefrom, and natural gas. “Biorenewable fuels”as used herein is understood to mean any fuel which is derived fromresources other than petroleum. Such resources include, but are notlimited to, corn, maize, soybeans and other crops; grasses, such asswitchgrass, miscanthus, and hybrid grasses; algae, seaweed, vegetableoils; natural fats; and mixtures thereof. In an aspect, the biorenewablefuel can comprise monohydroxy alcohols, such as those comprising from 1to about 5 carbon atoms. Non-limiting examples of suitable monohydroxyalcohols include methanol, ethanol, propanol, n-butanol, isobutanol,t-butyl alcohol, amyl alcohol, and isoamyl alcohol. Preferred fuelsinclude diesel fuels.

The fuels herein are suitable for use in various internal combustionsystems or engines. The systems or engines may include both stationaryengines (e.g., engines used in electrical power generationinstallations, in pumping stations, etc.) and ambulatory engines (e.g.,engines used as prime movers in automobiles, trucks, road-gradingequipment, military vehicles, etc.). By combustion system or engineherein is meant, internal combustion engines, for example and not bylimitation, Atkinson cycle engines, rotary engines, spray guided, wallguided, and the combined wall/spray guided direct injection gasoline(“DIG” or “GDI”) engines, turbocharged DIG engines, supercharged DIGengines, homogeneous combustion DIG engines, homogeneous/stratified DIGengines, DIG engines outfitted with piezoinjectors with capability ofmultiple fuel pulses per injection, DIG engines with EGR, DIG engineswith a lean-NOx trap, DIG engines with a lean-NOx catalyst, DIG engineswith SN—CR. NOx control, DIG engines with exhaust diesel fuelafter-injection (post combustion) for NOx control, DIG engines outfittedfor flex fuel operation (for example, gasoline, ethanol, methanol,biofuels, synthetic fuels, natural gas, liquefied petroleum gas (LPG),and mixtures thereof.) Also included are conventional and advancedport-fueled internal combustion engines, with and without advancedexhaust after-treatment systems capability, with and withoutturbochargers, with and without superchargers, with and without combinedsupercharges turbocharger, with and without on-board capability todeliver additive for combustion and emissions improvements, and with andwithout variable valve timing. Further included are gasoline fueledhomogeneous charge compression ignition (HCCI) engines, diesel HCCIengines, two-stroke engines, diesel fuel engines, gasoline fuel engines,stationary generators, gasoline and diesel HCCI, supercharged,turbocharged, gasoline and diesel direct injection engines, enginescapably of variable valve timing, leanburn engines, engines capable ofinactivating cylinders or any other internal combustion engine. Stillfurther examples of combustion systems include any of the above-listedsystems combined in a hybrid vehicle with an electric motor.

Accordingly, aspects of the present application are directed to methodsof or the use of the quaternary ammonium compounds herein for reducinginjector deposits in an internal combustion system or engine or within afuel system for an internal combustion system or engine, cleaning-upfouled injectors, or un-sticking injectors. In another aspect, thequaternary ammonium compounds described herein or fuel containing thequaternary ammonium compounds herein may be combined with one or more ofpolyhydrocarbyl-succinimides, -acids, -amides, -esters, -amide/acids and-acid/esters, reaction products of polyhydrocarbyl succinic anhydrideand aminoguanidine and its salts, Mannich compounds, and mixturesthereof. In other aspects, the methods or use include injecting ahydrocarbon-based fuel comprising a quaternary ammonium compounds of thepresent disclosure through the injectors of the engine into thecombustion chamber, and igniting the fuel to prevent or remove depositson fuel injectors, to clean-up fouled injectors, and/or to unstickinjectors. In some aspects, the method may also comprise mixing into thefuel at least one of the optional additional ingredients describedabove.

EXAMPLES

The following examples are illustrative of exemplary embodiments of thedisclosure. In these examples as well as elsewhere in this application,all ratios, parts, and percentages are by weight unless otherwiseindicated. It is intended that these examples are being presented forthe purpose of illustration only and are not intended to limit the scopeof the invention disclosed herein.

Comparative Example 1

A comparative quaternary ammonium salt was prepared in a mannerconsistent to various examples (e.g., Example 2, Example 10, etc.) in EP2 531 580 B1. Comparative preparative additive A (a comparativepreparatory polyisobutenyl succinimide, PIBSI) was prepared as follows:207.95 grams (0.218 equivalents of anhydride) of polyisobutenyl succinicanhydride (PIMA, made with about 1000 average MW polyisobutylene, PIB,and maleic anhydride) and 92.60 grams of toluene were charged in a 1liter reaction flask equipped with Dean-Stark trap. Under nitrogen, themixture was stirred and heated to 90° C. Over about 10 minutes, 22.30grams of dimethylamino propylamine (DMAPA) was added. The temperaturewas increased to about 165° C. and held for 4 hours while removingwater. Toluene was removed under vacuum. IR spectroscopy of the productconfirmed formation of the succinimide.

Comparative additive B (a comparative quaternary ammonium salt) wasprepared as follows: 100.53 grams (0.0970 moles) of Additive A and 14.76grams (0.0970 moles) of methyl salicylate were charged in a 250 mlreaction flask. The mixture was heated under nitrogen to 140° C. andheld for 7 hours. ¹H NMR spectroscopy of the product confirmed formationof a quaternary ammonium salt.

Example 1

Additive C (preparatory oleyl amide) was prepared as follows: 249.05grams (0.882 moles) of oleic acid and 60.35 grams of toluene wherecharged in a 1 liter reaction flask equipped with Dean-Stark trap. Undernitrogen, the mixture was stirred and heated to 100° C. Over about 20minutes, 128.77 grams (0.882 moles) of 3-(2-(dimethylamino)ethoxy)propylamine (DMAEPA) was added. The temperature was increased to about165° C. and held for 4 hours while removing water. Toluene was removedunder vacuum. IR spectroscopy of the product confirmed formation of theamide.

Additive D (an inventive quaternary ammonium salt) was prepared asfollows: 7.50 grams (0.0183 moles) of Additive C and 2.80 grams (0.0184moles) of methyl salicylate were charged in a thick walled glass tubeand sealed. The mixture was heated under nitrogen to 140° C. and heldfor 12 hours. ¹H NMR spectroscopy of the product confirmed formation ofthe quaternary ammonium salt.

Example 2

Additive E (preparatory ASA succinimide) was prepared as follows: 270.93grams (0.679 equivalents of anhydride) of a C₂₀₋₂₄ alkenyl succinicanhydride (ASA) and 105.73 grams of toluene were charged in a 1 literreaction flask equipped with Dean-Stark trap. Under nitrogen, themixture was stirred and heated to 100° C. Over about 15 minutes, 99.13grams (0.679 moles) of 3-(2-(dimethylamino)ethoxy)propylamine (DMAEPA)was added. The temperature was increased to about 160° C. and held for 4hours while removing water. Toluene was removed under vacuum. IRspectroscopy of the product confirmed formation of the amide.

Additive F (inventive quaternary ammonium salt) was prepared as follows:106.71 grams (0.202 moles) of Additive E and 30.78 grams (0.202 moles)of methyl salicylate were charged in a 250 ml reaction flask. Themixture was heated under nitrogen to 140° C. and held for 6 hours. ¹HNMR spectroscopy of the product confirmed formation of the quaternaryammonium salt.

Example 3

Additive G (preparatory PIBSI) was prepared as follows: 207.75 grams(0.218 equivalents of anhydride) of PIBSA (made with about 1000 MW PIBand maleic anhydride) and 67.96 grams of toluene were charged in a 1liter reaction flask equipped with Dean-Stark trap. Under nitrogen, themixture was stirred and heated to 100° C. Over about 15 minutes, 30.24grams (0.207 moles) of 3-(2-(dimethylamino)ethoxy)propylamine (DMAEPA)was added. The temperature was increased to about 160° C. and held for 3hours while removing water. Toluene was removed under vacuum. IRspectroscopy of the product confirmed formation of the succinimide.

Additive H (inventive quaternary ammonium salt) was prepared as follows:67.20 grams (0.057 moles) of Additive G and 8.69 grams (0.057 moles) ofmethyl salicylate were charged in a 250 ml reaction flask. The mixturewas heated under nitrogen to 140° C. and held for 6 hours. ¹H NMRspectroscopy of the product confirmed formation of the quaternaryammonium salt.

Example 4

Additive I (preparatory PIBSI) was prepared as follows: 287.50 grams(0.126 equivalents of anhydride) of PIBSA (made with 2300 MW PIB andmaleic anhydride) and 96.15 grams of toluene were charged in a 1 literreaction flask equipped with Dean-Stark trap. Under nitrogen, themixture was stirred and heated to 100° C. Over about 5 minutes, 18.20grams (0.125 moles) of 3-(2-(dimethylamino)ethoxy)propylamine (DMAEPA)was added. The temperature was increased to about 160° C. and held for 4hours while removing water. Toluene was removed under vacuum. IRspectroscopy of the product confirmed formation of the succinimide.

Additive J (inventive quaternary ammonium salt) was prepared as follows:95.37 grams (0.0396 moles) of Additive I and 6.02 grams (0.0396 moles)of methyl salicylate were charged in a 250 ml reaction flask. Themixture was heated under nitrogen to 140° C. and held for 6 hours. ¹HNMR spectroscopy of the product confirmed formation of the quaternaryammonium salt.

Example 5

Additive K (preparatory PIBSI) was prepared as follows: 283.62 grams(0.298 equivalents of anhydride) of PIBSA (made with about 1000 MW PIBand maleic anhydride) and 82.31 grams of toluene were charged in a 1liter reaction flask equipped with Dean-Stark trap. Under nitrogen, themixture was stirred and heated to 100° C. Over about 15 minutes, 47.37grams (0.298 moles) of N,N dimethyldipropylene triamine (DMAPAPA) wasadded. The temperature was increased to about 160° C. and held for 2hours while removing water. Toluene was removed under vacuum. IRspectroscopy of the product confirmed formation of the succinimide.

Additive L (inventive quaternary ammonium salt) was prepared as follows:78.31 grams (0.0717 moles) of Additive K and 10.90 grams (0.0717 moles)of methyl salicylate were charged into a 250 ml reaction flask. Themixture was heated under nitrogen to 160° C. and held for 6 hours. ¹HNMR spectroscopy of the product confirmed formation of the quaternaryammonium salt.

Example 6

The above quaternary ammonium salt additives from the comparative andinventive Examples were evaluated in a diesel fuel using an XUD-9 test(CEC F-23-A-01). The XUD-9 test method evaluates the capability of afuel to control the formation of deposits on the injector nozzles of anindirect injection diesel engine. Results of tests run according to theXUD-9 test method were expressed in terms of the percentage airflow lossat various injector needle lift points. Airflow measurements wereaccomplished with an airflow rig complying with ISO 4010.

Prior to conducting the test, the injector nozzles were cleaned andchecked for airflow at 0.05, 0.1, 0.2, 0.3 and 0.4 mm lift. Nozzles werediscarded if the airflow was outside of the range 250 ml/min to 320ml/min at 0.1 mm lift. The nozzles were assembled into the injectorbodies and the opening pressures set to 115±5 bar. A slave set ofinjectors was also fitted to the engine. The previous test fuel wasdrained form the system. The engine was run for 25 minutes in order toflush through the fuel system. During this time all the spill-off fuelwas discarded and not returned. The engine was then set to test speedand load and all specified parameters checked and adjusted to the testspecification. The slave injectors were then replaced with the testunits. Air flow was measured before and after the test. An average of 4injector flows at 0.1 mm lift was used to calculate the percent offouling. The degree of flow remaining=100−percent of fouling. Theresults are provided in Table 1 below.

TABLE 1 XUD-9 Test Results Active Treat Rate Average Flow Loss Additive(ppm by wt) (%) None — 70 B (Comparative) 15 45 D 10 9 F 10 36 H 10 10 H15 5 H 30 0 J 15 43 L 15 45

All of the inventive additives performed as well as or better (had thesame or lower flow loss) than the comparative additive. Moreover,certain inventive additives demonstrated dramatically improveddetergency at a lower treat rate that the comparative additives.

Example 7

A DW-10B diesel engine was also run to determine the inventive additivesability to clean up fouled injectors using a test outlined in CECF-98-08. Using the test cycle and dopant (1 ppm Zn as zinc neodecanoate)used in CEC F-98-08, inventive additives H and D were evaluated fortheir ability in diesel fuel to remove (clean up) deposits. To performthis evaluation, the engine was first run with zinc dopant in the fuel,resulting in a power loss due to fouling of the injector holes. Then,the engine was run on fuel containing both the zinc dopant and detergentadditive(s). A more detailed description of this protocol can be foundin U.S. Pat. No. 8,894,726 B2 (Column 9), which is incorporated hereinby reference and further discussed below. The results are shown in Table3.

Diesel Engine Test Protocol:

The DW-10 test was developed by Coordinating European Council (CEC) todemonstrate the propensity of fuels to provoke fuel injector fouling andcan also be used to demonstrate the ability of certain fuel additives toprevent or control these deposits. Additive evaluations used theprotocol of CEC F-98-08 for direct injection, common rail diesel enginenozzle coking tests. An engine dynamometer test stand was used for theinstallation of the Peugeot DW10 diesel engine for running the injectorcoking tests. The engine was a 2.0 liter engine having four cylinders.Each combustion chamber had four valves and the fuel injectors were DIpiezo injectors that have a Euro V classification.

The core protocol procedure consisted of running the engine through acycle for 8-hours and allowing the engine to soak (engine off) for aprescribed amount of time. The foregoing sequence was repeated fourtimes. At the end of each hour, a power measurement was taken of theengine while the engine was operating at rated conditions. The injectorfouling propensity of the fuel was characterized by a difference inobserved rated power between the beginning and the end of the testcycle.

Test preparation involved flushing the previous test's fuel from theengine prior to removing the injectors. The test injectors wereinspected, cleaned, and reinstalled in the engine. If new injectors wereselected, the new injectors were put through a 16-hour break-in cycle.Next, the engine was started using the desired test cycle program. Oncethe engine was warmed up, power was measured at 4,000 RPM and full loadto check for full power restoration after cleaning the injectors. If thepower measurements were within specification, the test cycle wasinitiated. Table 2 below provides a representation of the DW-10 cokingcycle that was used to evaluate the fuel additives according to thedisclosure.

TABLE 2 One hour representation of DW-10 coking cycle Duration EngineBoost air after Step (minutes) speed (rpm) Load (%) Torque (Nm)Intercooler (° C.) 1 2 1750 20 62 45 2 7 3000 60 173  50 3 2 1750 20 6245 4 7 3500 80 212  50 5 2 1750 20 62 45 6 10 4000 100 * 50 7 2 1250 1025 43 8 7 3000 100 * 50 9 2 1250 10 25 43 10 10 2000 100 * 50 11 2 125010 25 43 12 7 4000 100 * 50

Fuel additives D and H from Examples 1 and 3 were tested using theforegoing engine test procedure in an ultra-low sulfur diesel fuelcontaining zinc neodecanoate, 2-ethylhexyl nitrate, and a fatty acidester friction modifier (base fuel). A “dirty-up” phase consisting ofbase fuel only with no additive was initiated, followed by a “clean-up”phase consisting of base fuel plus additive as noted in Table 3 below.All runs were made with 8 hour dirty-up and 8 hour clean-up unlessindicated otherwise. The percent power recovery was calculated using thepower measurement at end of the “dirty-up” phase and the powermeasurement at end of the “clean-up” phase. The percent power recoverywas determined by the following formula: Percent Powerrecovery=(DU−CU)/DU×100, wherein DU is a percent power loss at the endof a dirty-up phase without the additive, CU is the percent power at theend of a clean-up phase with the fuel additive, and power is measuredaccording to CEC F98-08 DW10 test.

TABLE 3 DW-10B Test Results - Clean Up Power Loss Active Treat PowerLoss after 8 hours Power Rate(s) after Dirty Up of Clean Up RecoveryAdditive(s) (ppm by wt) (%) (%) (%) H 45 4.53 0.59 87 H and D 30 and 55.80 2.03 65

Example 8

Another evaluation involving the DW-10B test was run to determine theadditives ability to remove carboxylate deposits in a diesel engine.These types of deposits can form on internal moving parts causinginjector sticking on cold start. A description of the test protocol canbe found in U.S. Pat. No. 8,529,643 B2 (Columns 11-12), which isincorporated herein by reference and further discussed below, with theexception that the fouling dopants were 0.5 ppm by wt sodium as sodiumnaphthenate and 10 ppm by wt dodecenyl succinic acid (DDSA).

In this example, the effect of inventive additives on diesel fuelcontaminated with carboxylate salts for high pressure common rail dieselfuel systems was evaluated. An engine test was used to demonstrate thepropensity of fuels to provoke fuel injector sticking and was also usedto demonstrate the ability of certain fuel additives to prevent orcontrol the internal deposits in the injectors. An engine dynamometertest stand was used for the installation of a Peugeot DW10 diesel enginefor running the injector sticking tests. The engine was a 2.0 literengine having four cylinders. Each combustion chamber had four valvesand the fuel injectors were DI piezo injectors have a Euro Vclassification.

The core protocol procedure consisted of running the engine through acycle for 8-hours and allowing the engine to soak (engine off) for aprescribed amount of time. The injector performance was thencharacterized by measuring the cylinder exhaust temperature for eachcylinder. A test was stopped and considered to have failed (one or moreinjectors sticking) if the exhaust temperature of any cylinder was morethan 65° C. above any other cylinder exhaust temperature at any point intime. A test was also considered to have failed if after allowing theengine to cool to ambient temperature, a cold start showed a temperaturedifference of 45° C. or more in cylinder exhaust temperatures. Stickingof the needle and thus failure could also be confirmed by disassemblingthe injector and subjectively determining the force required to removethe needle from the nozzle housing. Cleanliness tests were run forkeep-clean performance as well as clean-up performance.

Test preparation involved flushing the previous test's fuel from theengine prior to removing the injectors. The test injectors wereinspected, cleaned, and reinstalled in the engine. If new injectors wereselected, the new injectors were put through a 16-hour break-in cycle.Next, the engine was started using the desired test cycle program. Oncethe engine was warmed up, power was measured at 4,000 RPM and full loadto check for full power restoration after cleaning the injectors. If thepower measurements were within specification, the test cycle wasinitiated.

The diesel engine nozzle sticking tests were conducted using the PeugeotDW-10 engine following the protocol of Table 2 above. For keep-cleantesting, the engine was run with diesel fuel contaminated with metalcarboxylate salts and with the detergent additive indicated in Table 5below. For clean-up testing, the engine was first run with diesel fuelcontaminated with metal carboxylate salts without a detergent additiveto establish a baseline of stuck fuel injectors. Next, the engine wasrun with the same fuel containing the detergent additive indicated. Inall of the tests, the fuels tested contained 200 ppmv lubricity modifierand 1600 ppmv cetane improver, 0.5 ppmw sodium as sodium naphthenate and10 ppmw dodecenyl succinic acid (DDSA), 3 ppmw of NaOH, and 25 ppmwv ofwater. At the beginning of the test, no injector sticking was indicatedby a uniform exhaust gas temperature for all 4-cylinders as shown inTable 5 below. However, a cold start of the engine after 8 hours showedinjector sticking as also shown in Table 5 due to the increasedtemperature differential between the cylinders. As also shown in Table5, Detergent Additive H greatly reduced the maximum exhaust gastemperature difference, indicating that the injectors were no longersticking.

TABLE 5 DW-10B Test Results - Carboxylate Deposit Removal Active MaximumExhaust Detergent Gas Temperature Engine Run Additive Difference on TimeDetergent Treat Rate Cold Start (hrs) Dopants Additive (ppm by wt) (°C.) Start of Test None None — 11 16 Na/DDSA None — 78 24 Na/DDSA H 45 2532 Na/DDSA H 45 22

Example 9

Inventive additive H from Example 3 above was further tested for itsability to clean-up fouled injectors in a gasoline direct injection(GDI) engine using the procedure set forth in Shanahan, C., Smith, S.,and Sears, B., “A General Method for Fouling Injectors in GasolineDirect Injection Vehicles and the Effects of Deposits on VehiclePerformance,” SAE Int. J. Fuels Lubr. 10(3):2017,doi:10.4271/2017-01-2298, which is incorporated herein by reference anddiscussed further below.

The GDI testing involved the use of a fuel blend to accelerate thedirty-up phase or injector fouling of the GDI engine. The acceleratedfuel blend included 409 ppmw of di-tert-butyl disulfide (DTBDS,contributing about 147 ppmw active sulfur to the fuel) and 286 ppmw oftert-butyl hydrogen peroxide (TBHP). The test involved running a 2013Kia Optima having a 2.4 L, 16 valve, inline 4 gasoline direct injectionengine on a mileage accumulation dynamometer. The engine was run usingthe Quad 4 drive cycle as set forth in the above noted SAE paper (SAE2017-01-2298) and as set forth in Table 6 below. Injector cleanlinesswas measured using Long Term Fuel Trim (LTFT) as reported by the vehicleengine control unit (ECU) and was measured relative to the accumulatedmileage. Results of the GDI testing are shown below in Table 7.

TABLE 6 Quad 4 Drive Cycle Time (min) 0 0.5 11.75 11.95 28.35 28.55 39.540 64.5 64.75 82.75 83 99.4 100 105 Speed (mph) 0 40 40 55 55 40 40 5555 25 25 55 55 0 0 Acceleration 1.3 1.3 −1.3 0.5 −2 2 −1.5 (mph/sec)Steady State 11.25 16.4 10.95 24.5 18 16.4 5 Duration (min)

TABLE 7 GDI Test Results Change in LTFT Vehicle Miles from Start ofDetergent Additive Treat Accumulated test with clean Clean Test #Segment Phase Additive Rate, ppmw During Segment injectors (%) Up (%) 11 Dirty Up None (Base) — 4453 9.13 2 Clean Up Additive H 30 1029 0.93 902 1 Dirty Up None (Base) — 3641 7.93 2 Clean Up Additive H 15 1029 3.7553

It is noted that, as used in this specification and the appended claims,the singular forms “a,” “an,” and “the,” include plural referents unlessexpressly and unequivocally limited to one referent. Thus, for example,reference to “an antioxidant” includes two or more differentantioxidants. As used herein, the term “include” and its grammaticalvariants are intended to be non-limiting, such that recitation of itemsin a list is not to the exclusion of other like items that can besubstituted or added to the listed items

For the purposes of this specification and appended claims, unlessotherwise indicated, all numbers expressing quantities, percentages orproportions, and other numerical values used in the specification andclaims, are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that can vary depending upon thedesired properties sought to be obtained by the present disclosure. Atthe very least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, each numericalparameter should at least be construed in light of the number ofreported significant digits and by applying ordinary roundingtechniques.

It is to be understood that each component, compound, substituent orparameter disclosed herein is to be interpreted as being disclosed foruse alone or in combination with one or more of each and every othercomponent, compound, substituent or parameter disclosed herein.

It is further understood that each range disclosed herein is to beinterpreted as a disclosure of each specific value within the disclosedrange that has the same number of significant digits. Thus, for example,a range from 1 to 4 is to be interpreted as an express disclosure of thevalues 1, 2, 3 and 4 as well as any range of such values.

It is further understood that each lower limit of each range disclosedherein is to be interpreted as disclosed in combination with each upperlimit of each range and each specific value within each range disclosedherein for the same component, compounds, substituent or parameter.Thus, this disclosure to be interpreted as a disclosure of all rangesderived by combining each lower limit of each range with each upperlimit of each range or with each specific value within each range, or bycombining each upper limit of each range with each specific value withineach range. That is, it is also further understood that any rangebetween the endpoint values within the broad range is also discussedherein. Thus, a range from 1 to 4 also means a range from 1 to 3, 1 to2, 2 to 4, 2 to 3, and so forth.

Furthermore, specific amounts/values of a component, compound,substituent or parameter disclosed in the description or an example isto be interpreted as a disclosure of either a lower or an upper limit ofa range and thus can be combined with any other lower or upper limit ofa range or specific amount/value for the same component, compound,substituent or parameter disclosed elsewhere in the application to forma range for that component, compound, substituent or parameter.

While particular embodiments have been described, alternatives,modifications, variations, improvements, and substantial equivalentsthat are or can be presently unforeseen can arise to applicants orothers skilled in the art. Accordingly, the appended claims as filed andas they can be amended are intended to embrace all such alternatives,modifications variations, improvements, and substantial equivalents.

What is claimed is:
 1. A fuel additive comprising a quaternary ammoniumsalt formed by the reaction of an alkyl carboxylate with a compoundobtained by reacting a hydrocarbyl substituted acylating agent and anamine, wherein the amine has the structure

wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, —C(O)NR′; R₁ and R₂ are independently alkyl groupscontaining 1 to 8 carbon atoms; and R′ is independently a hydrogen or agroup selected from C₁₋₆ aliphatic, phenyl, or alkylphenyl.
 2. The fueladditive of claim 1, wherein the alkyl carboxylate is alkyl oxalate,alkyl salicylate, or a combination thereof.
 3. The fuel additive ofclaim 1, wherein the alkyl group in the alkyl carboxylate is C1 to C6alkyl.
 4. The fuel additive of claim 1, wherein A is—(CH₂)_(r)—[X—(CH₂)_(r′)]_(p)— with each of r, r′, and p independentlybeing 1, 2, 3, or 4 and X being O or NR″ with R″ being hydrogen or ahydrocarbyl group.
 5. The fuel additive of claim 4, wherein X is oxygen6. The fuel additive of claim 1, wherein the amine is selected from3-(2-(dimethyl amino)ethoxy)propylamine,N,N-dimethyldipropylenetriamine, and mixtures thereof.
 7. The fueladditive of claim 1, wherein the hydrocarbyl substitued acylating agentis selected from a hydrocarbyl substituted dicarboxylic acid oranhydride derivative thereof, a fatty acid, or mixtures thereof.
 8. Thefuel additive of claim 1, wherein the hydrocarbyl substituent has anumber average molecular weight of about 200 to about 2500 as measuredby GPC using polystyrene as a calibration reference.
 9. A fuelcomposition comprising a major amount of a fuel and a minor amount of aquaternary ammonium salt formed by the reaction of an alkyl carboxylatewith a compound obtained by reacting a hydrocarbyl substituted acylatingagent and an amine, wherein the formed quaternary ammonium salt has thestructure

wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, —C(O)NR′; R₁, R₂, and R₃ are independently alkyl groupscontaining 1 to 8 carbon atoms; and R′ is independently a hydrogen or agroup selected from C₁₋₆ aliphatic, phenyl, or alkylphenyl; and R₄ andR₅ are independently selected from a hydrogen, an acyl group, or ahydrocarbyl substituted acyl group, wherein if one of R₄ or R₅ ishydrogen, then the other of R₄ and R₅ is the acyl group or thehydrocarbyl substituted acyl group, if both R₄ and R₅ include carbonylmoieties, then one of R₄ and R₅ includes the acyl group and the other ofR₄ and R₅ includes the hydrocarbyl substitued acyl group, and R₄ and R₅together with the N atom to which they are attached, combine to form aring moiety; and M⁻ is a carboxylate.
 10. The fuel composition of claim9, comprising about 1 to about 100 ppm of the quaternary ammonium salt.11. The fuel composition of claim 9, wherein the carboxylate is oxalate,salicylate, or combinations thereof.
 12. The fuel composition of claim9, wherein A is —(CH₂)_(r)—[X—(CH₂)_(r′)]_(p)— with each of r, r′, and pindependently being 1, 2, 3, or 4 and X being O or NR″ with R″ beinghydrogen or a hydrocarbyl group.
 13. The fuel composition of claim 12,wherein X is oxygen.
 14. The fuel composition of claim 12, wherein Aincludes a moiety derived from 3-(2-(dimethylamino)ethoxy)propylamine,N,N-dimethyldipropylenetriamine, or mixtures thereof.
 15. The fuelcomposition of claim 9, wherein R₄ and R₅, together with the nitrogenatom to which they are attached, combine to form a hydrocarbylsubstituted succinimide.
 16. The fuel composition of claim 15, whereinthe hydrocarbyl substituent has a number average molecular weight ofabout 200 to about 2500 as measured by GPC using polystyrene as acalibration reference.
 17. The fuel composition of claim 9, wherein thehydrocarbyl substituent of R₄ or R₅ has a number average molecularweight of about 200 to about 2500 as measured by GPC using polystyreneas a calibration reference.
 18. A method of operating a fuel injectedengine to provide improved engine performance, the method comprisingcombusting in the engine a fuel composition including a major amount offuel and about 1 to about 100 ppm of a quaternary ammonium salt formedby the reaction of an alkyl carboxylate with a compound obtained byreacting a hydrocarbyl substituted acylating agent and an amine, whereinthe amine has the structure

wherein A is a hydrocarbyl linker with 2 to 10 carbon units andincluding one or more carbon units thereof independently replaced with abivalent moiety selected from the group consisting of —O—, —N(R′)—,—C(O)—, —C(O)O—, —C(O)NR′; R₁ and R₂ are independently alkyl groupscontaining 1 to 8 carbon atoms; and R′ is independently a hydrogen or agroup selected from C₁₋₆ aliphatic, phenyl, or alkylphenyl.
 19. Themethod of claim 18, wherein the improved engine performance is anaverage flow loss of about 45 percent or less when measured according toa CEC F-23-01 (XUD-9) test.
 20. A method of claim 18, wherein the formedquaternary ammonium salt has the structure

wherein A includes 2 to 6 carbon units with one carbon unit thereofindependently replaced with —O— or —NH—; R₁, R₂, and R₃ areindependently alkyl groups containing 1 to 8 carbon atoms; and R₄ and R₅are independently selected from a hydrogen, an acyl group, or ahydrocarbyl substituted acyl group, wherein if one of R₄ or R₅ ishydrogen, then the other of R₄ and R₅ is the acyl group or thehydrocarbyl substituted acyl group, if both R₄ and R₅ include carbonylmoieties, then one of R₄ and R₅ includes the acyl group and the other ofR₄ and R₅ includes the hydrocarbyl substitued acyl group, and R₄ and R₅together with the N atom to which they are attached, combine to form aring moiety; and M⁻ is a carboxylate.
 21. The method of claim 20,wherein the carboxylate includes oxalate, salicylate, or combinationsthereof.
 22. The method of claim 20, wherein the hydrocarbyl substituenthas a number average molecular weight of about 200 to about 2500 asmeasured by GPC using polystyrene as a calibration reference.